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Kinetic Isotope Effect as a Tool To Investigate the Oxygen Reduction Reaction on Pt-based Electrocatalysts – Part I: High-loading Pt/C and Pt Extended Surface |
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| Authors: | Thomas Y George Dr Tristan Asset Arezoo Avid Prof Plamen Atanassov Prof Iryna V Zenyuk |
| Institution: | 1. Department of Chemical and Biological Engineering, Tufts University, Medford, MA, USA
These authors contributed equally to this work;2. Department of Chemical and Biomolecular Engineering, University of California Irvine, Irvine, CA, USA National Fuel Cell Research Center, University of California Irvine, Irvine, CA, USA These authors contributed equally to this work;3. Department of Chemical and Biomolecular Engineering, University of California Irvine, Irvine, CA, USA National Fuel Cell Research Center, University of California Irvine, Irvine, CA, USA;4. Department of Chemical and Biomolecular Engineering, University of California Irvine, Irvine, CA, USA |
| Abstract: | Kinetic isotope effect (KIE) was used to study the rate-determining step for oxygen reduction reaction (ORR) on dispersed Pt/C electrocatalyst and polycrystalline Pt (Pt-poly). KIE is defined as the ratio of the kinetic current measured in protonated electrolyte versus deuterated electrolyte, with KIE values larger than one indicating proton participation in the rate-determining step. The effect of poisoning anions on the platinum rate determining step is investigated by assessing the KIE in perchloric (non-poisoning) and sulfuric acid-based electrolytes. The kinetics currents were calculated using the Koutechy-Levich and Tafel analysis. A KIE of 1 was observed for Pt/C (with a 40 wt.% Pt loading) and Pt-poly, thus indicating that, on 40 wt. % Pt/C and Pt-poly, the rate determining step is proton independent. |
| Keywords: | kinetic isotope effect oxygen reduction reaction PEM fuel cells platinum rate-determining step |